Yes, that's why I would expect it to smoke Postgres here, in process is orders of magnitude faster. Do you really need concurrency here when you can do 10-100k+ inserts per second?
If 100k users each hit purchase button at the same time will sqlite write it in 1 second?
This is different than 1 user doing the purchase for 100k fans
I mean it depends on the query and what you're doing of course, but it's not impossible to reach writes/s in the 80k range.
Also surprised. My yardstick was this post which showed SQLite beating Postgres in a Django app. Benchmarking is hard, and the author said the Postgres results were not tuned to the same degree as SQLite, so buyer beware.
https://blog.pecar.me/django-sqlite-benchmark